Arsenal, West Ham and Newcastle left it late to beat the transfer deadline and make last-minute signings on Friday night.
Arsenal have signed France international midfielder Lassana Diarra from Chelsea on a 'long-term contract' for an undisclosed fee.
West Ham confirmed they signed Henri Camara from Wigan and Nolberto Solano from Newcastle, while the Magpies beat the transfer deadline to complete the signings of Habib Beye and Abdoulaye Faye.
Versatile 22-year-old Diarra had found first-team opportunities limited at Stamford Bridge and told the club's website, arsenal.com: 'I have great respect for the manager Arsene Wenger and am attracted by the style of football that the team plays.
'Of course I am excited by what the future holds and keen to play my part in helping Arsenal fight for trophies this season and for years to come.'
Striker Camara has signed on a season-long loan at Upton Park while Solano joins on a one-year contract with the option of another year.
Neither signed in time to play for the Hammers against Reading today.
Defensive pair Beye and Faye had been expected to make the move to St James' Park but left it late to confirm their three-year deals.
Middlesbrough overcame a late complication to complete the £5million signing of Gary O'Neil from Portsmouth less than an hour before the transfer deadline.
The 24-year-old underwent a medical on Teesside after the two clubs agreed a £5million fee.
Boro boss Gareth Southgate told Sky Sports: 'We've just completed the deal, we've very pleased and I'm looking forward to getting home to bed!'
Southgate was also able to complete the signing of Mohamed Shawky from Egyptian side Al-Ahly for £650,000 on a three-year deal, while releasing the experienced Jason Euell to make a free transfer to Southampton.
As the midnight deadline approached, Reading signed Liam Rosenior from Fulham with Seol Ki-Hyeon moving in the opposite direction.
Fulham were one of the most active teams, Danny Murphy also joining on a one-year deal from Tottenham.
Fulham midfielder Papa Bouba Diop became Portsmouth's second signing of transfer deadline day.
Having already signed spent £4million to sign Chelsea right-back Glen Johnson on a four-year contract, Pompey boss Harry Redknapp signed the Senegal international on a three-year contract for an undisclosed fee.
One player who had already departed Fratton Park was Dejan Stefanovic, who joined Fulham for £1million on a two-year deal, subject to a work permit.
Elsewhere, the busiest managers could be found in the midlands with Aston Villa, Birmingham and Derby all making moves.
Martin O'Neill's pursuit of defender Curtis Davies finally came to a successful conclusion in what could be a potential club-record deal.
The West Brom centre-half secured a season-long loan at Villa with a view to a permanent switch which would be worth an initial £8.5million, possibly rising to £10million with add-ons.
O'Neill, who also signed Zat Knight this week, then made Togo midfielder Moustapha Salifou his third buy during the last 48 hours, signing him from Swiss club FC Wil on a one-year contract.
Scotland striker Kenny Miller swapped Celtic Park for Pride Park after joining Derby for an undisclosed fee.
Birmingham boss Steve Bruce secured the services of free agent Mohammed Kallon, midfielder Wilson Palacios on loan from Honduran club Olimpia until the end of December and Borja Oubina on a season-long loan from Celta Vigo with 'minutes to spare'.
Manchester City striker Bernardo Corradi joined Parma on loan until the end of the season.
Wigan boss Chris Hutchings made his ninth signing of the summer by bringing striker Marcus Bent in on loan from Charlton. Bent's arrival has allowed Wigan to sell Caleb Folan to Hull.
Liverpool's Anthony Le Tallec has joined French side Le Mans on loan with a view to a permanent deal.
Crystal Palace have signed Manchester City striker Paul Dickov on loan until January while Finland international Shefki Kuqi has joined Fulham on a similar deal.